Zeolite Case Study

3. Results and discussion:
3.1. Characterization of Zeolites:
3.1.1. Cation exchange capacity (CEC):
CEC is directly related to the amount of aluminum present in the framework. It decreases with increasing the Si/Al ratio. Usually natural zeolite has CEC ranged between 100 and 400 meq/100g (Yukselen-Aksoy, 2010). By using ammonium acetate method, CEC of natural Syrian zeolite ranged between 100 meq/100g for MK and 120 meq/100g for both OZ and JS. The relative low values of CEC may be correlated with the high Si/Al ratio in the samples as noted by the XRF analysis data (El-Kammar, et al., 2014).
3.1.2. Textural properties:
Natural zeolites have a unique crystalline structure with an aluminosilicate tetrahedral framework arranged in rings, which further

Zeolite tends to neutralize the solution's acidity by exchange of H+ with the cations initially present in their structures. At higher pH level, the concentration of the H+ ions as competing ion decreases and that leads to an increase in the amount of the sorbed metals (Pandey, et al., 2015).
The amount of complex hydrated forms of the metals increases with increasing pH that intensifies adsorption. The almost complete removal of Cu may be attributed to the contribution of hydroxide precipitation with specific adsorption more than Cd. The final pH of solution reached 6.8 for Cd and 7.6 for Cu (Fig. 6).
As can be seen in Fig. 6, the removal percent of Cd and Cu has slight variations in the pH range 5-7 for three zeolite samples. Therefore, to ensure the highest removal of metal ions from the solution by the sorption process and reduce ions precipitation, the normal pH of synthetic solution 5.5-6, has been selected as an optimum pH for further adsorption experiments of both